Over the past 3-decades (29-years precisely), SSH has been a secure means of communication between UNIX based systems.

Founded in the year 1995 by a finished based computer scientist Tatu Ylonen, the protocol is known to have replaced less secure protocols such as Telnet, RSH, and Rlogin.

So, what is SSH?

SSH which stands for Secure Shell, is a protocol which is used to create a secure communication channel or medium between two network hosts. The service runs on port 22 and ensures that all data or files passing through the communicating medium are encrypted and unreadable.

This data encryption guarantees information confidentiality, and integrity between the two communicating parties (i.e. client and server).

…Founded in the year 1995 by a finished based computer scientist Tatu Ylonen. Image-source: Fixitgearware (Created with DALL-3)

Over the years, SSH has come to be a reliable source of communication. The protocol is known to support data encryption and provides authentication in the cause of data transportation across private, public, and unsecure networks.


SSH Clients, are a means by which a connection is made or established between remote systems, servers, or networks. Common implementation of a secure communication between an SSH client and a remote server, can be seen in GitHub repository communication, and the SSH client installed in the UNIX terminal on a user’s computer.

When a user tries to push a repository remotely from their personal computer to the GitHub account whose repository file they desire to update, the user needs to establish a communication using encryption keys.

Commonly known clients of SSH are PuTTY, Kitty, OpenSSH, WinSCP etc.  Multiple platforms are known to deploy the protocol in their infrastructure, with OpenSSH being the most widely used.

OpenSSH a renowned deployed platform, And A Project of OpenBSD.

OpenSSH Project:

The OpenSSH project is a project developed by the OpenBSD community, an organization known for writing various secure software’s. It implements standard SSH Protocols and is known to be used by various multinational companies.

To provide sustainability and cross platform usability, OpenSSH comes in two standard versions. The OpenBSD and the Portable OpenSSH. The Portable version is a small and secure version of OpenSSH, that supports only OpenBSD.

Building The Portable OpenSSH:

To provide stability in its functionality, and enable the OpenSSH to work across other platforms, the OpenBSD community added the necessary codes and configurations, in the OpenBSD version of OpenSSH; hence a reason for the Portable OpenSSH.  


SSH can be implemented on both the communicating server, and the client which establishes the secure communication to the server.

The Protocol comes in two versions, SSH V1, and SSH V2, which is defined under the RFC 4251. The version 1, was created to phase out the telnet protocol.

However, as computing power became more advanced, security researchers were able to crack this version of the protocol, leading to an influx in security flaws detected in the  version 1. This rise in security weaknesses gave birth to the SSH Version 2.

By default, all modern applications and software’s that uses this protocol in communication, have SSH version 2 protocol implemented.


All SSH servers are configured with a key pair. Each time a client tries to establish a connection to the SSH server, these key pairs are responsible for negotiating a temporary pair of keys that are shared between the two communicating hosts.

The temporary key pairs are then used by both the client, and  server, to generate a symmetric key which would be used to share data during the period the session is established, as well as additional keys to ensure data and connectivity integrity.

When an SSH connection or session is established for a long period of time; during the communication process, or during an exchange of voluminous data, the computer will negotiate a new temporary pair of keys, and a new symmetric key, to keep the communication active.

This mechanism of key exchange and generating is known as Cryptography, in Cybersecurity.  


OpenSSH has been an integral part of a secure communication that is widely trusted, and due to its trusted connectivity, organizations such as Microsoft, IBM, Cisco, Oracle, etc. are known to infuse OpenSSH in their various products, and infrastructure.




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